Casimir forces and quantum friction of finite-size atoms in relativistic trajectories

TL;DR

This paper develops a relativistic formalism to analyze quantum friction and Casimir forces on finite-size atoms with arbitrary trajectories near macroscopic objects, revealing velocity-dependent divergences and finite-size effects.

Contribution

It introduces a comprehensive relativistic framework for atoms modeled as Unruh-DeWitt detectors, accounting for finite size, arbitrary states, and boundary conditions, extending previous non-relativistic models.

Findings

Quantum friction diverges at velocities close to light speed.

Casimir force remains nearly velocity-independent at high speeds.

Finite detector size and interaction time induce quantum friction even for isolated non-inertial atoms.

Abstract

We study quantum friction and Casimir forces with a full-relativistic formalism for atoms modelled as Unruh-DeWitt detectors in the presence of arbitrary macroscopic objects. We consider the general case of atoms with arbitrary relativistic trajectories in arbitrary quantum states (including coherent superpositions) close to objects that impose arbitrary boundary conditions. Particularizing for conducting plates, we show that, for relative velocities close to the speed of light, the quantum friction diverges while the Casimir force is almost independent of the velocity. Since we include the effect of the finite size of the detector and the finite interaction time, we also obtain quantum friction when the detector is isolated but follows a non-inertial trajectory.